1. Field of the Invention
The present invention relates to an antenna and more particularly to an automobile antenna with a housing for storing a cable connecting an antenna element and communication equipment.
2. Prior Art
Generally, an automobile antenna for receiving broadcast waves of radio, etc. has a structure as described below. A cylindrical housing to store an antenna element is installed inside the automobile body and a rod antenna element is stored in this housing in such a manner as to be optionally inserted into or pulled out from the outside of the vehicle body. One end of the cable, such as a coaxial feeder cable, is connected to a conductive feeding tube, provided on the foregoing cylindrical antenna housing, so as to freely and slidably come into contact with the above-mentioned antenna element. The other end of the coaxial feeder cable is connected to communication equipment such as receiver set.
However, when the antenna constructed as described above is used for sending and receiving radio waves of a relatively high frequency such as wireless telephones in automobiles, the loss at the contact area between the antenna element and the conducting tube becomes great and stable transmission and reception cannot be achieved. Accordingly, it becomes necessary to directly connect one end of the coaxial feeder cable to the antenna element and the other end to the transceiver set through a fixing mount.
However, there is a problem in how to house the coaxial feeder cable which must be extended and contracted during extension/retraction of the antenna element. Various proposals have been made, but generally they require complicated structures which make it difficult to keep manufacturing costs low. Besides, their performance is not reliable. For example, Japanese Patent Application Laid-Open No. 1982-106303 discloses a car antenna extending/retracting mechanism wherein the car antenna has a motor-drive cable drum on which a cable winding portion is provided. The coaxial feeder cable is wound up on this winding portion and then led into a control room. Inside this control room, the coaxial feeder cable is wound around a cylinder in a neat spiral or scroll form so as to be stored.
However, in the above antenna mechanism, a control room and cable drum with a specific structure must be provided in relation to each other. As a result, the structure becomes very complicated, making it difficult to manufacture at a low cost. Furthermore, in the foregoing mechanism, while the coaxial feeder is orderly wound, if there is a dimensional error or operational variance, etc., excessive force is applied to the coaxial feeder cable, causing damage to it.